1. Field of the Invention
The present invention relates generally to a method and apparatus for recording real-time audio/video information onto recordable compact disc drives and particularly to achieving data consumption equilibrium to effectuate such real-time recording.
2. Description of the Prior Art
Most recordable compact disc drives are designed and optimized for use by Personal Computer (PC) with the source of the data to be recorded being either a hard disc drive or another recordable compact disc (CD-R) drive. In the latter cases, the size of the source data is fixed prior to the beginning of recording and is not transmitted in real-time to the media in which the source data is to be recorded.
In fact, currently, there are no known systems or methods for recording onto a CD-R drive from a source that generates data in real-time. Examples of such a source are an audio/video Motion Picture Expert Group (MPEG) board that captures audio/video information in real-time, compresses the same and records the compressed information in real-time to the CD-R drive. In such examples, the source data is transmitted at a predetermined average bit rate so that even though the transmission is in real-time, there is no variation in the data rate but the instantaneous size of data in the output buffer of the source is typically unknown. Since a CD-R drive has an input buffer that is fixed in size, there are a number of known problems with recording real-time data using prior art techniques. That is, data to be recorded must be transmitted to the compact disc drive at a fixed or constant rate, as this is done in real-time, similarly, the compact disc drive receives data at a fixed rate, in real-time. This creates a problem in that the rate of transmission and reception is not quite fixed at all times. Also, since there are typically 99 tracks in a CD, the data must be streamed as much as possible.
Another problem is preventing the source buffer from either overflowing or underflowing to ensure against the corruption of information being transmitted for recording. Another problem is preventing the CD-R buffer from either overflowing or underflowing to ensure against the corruption of information being recorded. Another issue with prior art systems and methods is the slow response time associated with starting and stopping of recording. That is, for example, using digital video recorders, when the record button is pressed, one would prefer the recording session to “start” immediately so that no information that is to be recorded is missed. Similarly, when the “stop” button is pressed, one would prefer that the recording session to stop immediately so as to prevent recording of undesirable information. Unfortunately however, compact disc drives designed for the traditional PCs have a slow response time due to having a large buffer size.
FIG. 1 shows a graph of buffer fullness vs. time for a prior art compact disc drive recorder device in a PC system. When recording starts, it takes to time until the input buffer is full and the drive operates in “steady-state”, where the input buffer oscillates between Smin and Smax values, during which time information or data can be accurately recorded.
Therefore, the need arises for accurately recording information transmitted in real-time on a compact disc drive without missing or corrupting the information to be recorded as a result of overflow or underflow of the source of the information to be recorded or overflow or underflow of the compact disc drive and to do so with minimal start up and stop recording time.